Pipe laying apparatus

ABSTRACT

For laying a string of pipe, a main sled and the trailer sled are adapted to be towed in a trench by a trenching machine. The sleds slide along the trench bottom on parallel runners and define a generally continuous pipe supporting surface inclined downwardly from the leading end toward the trailing end. The sled supports the end of the assembled pipe string, the next pipe section to be joined to the string for facilitating the assembly. The sleds are self centering within the trench and carry implements for preparing the trench bottom to receive the pipe string.

United States Patent Helton 1451 Aug. 29, 1972 [54] PIPE LAYINGAPPARATUS [72] Inventor: Marion P. Helton, P. O. Box 162,

Plummerville, Ark. 72127 22 Filed: Feb. 19, 1970 21 Appl.No.: 12,717

52 US. Cl. ...61/72.1, 193/35, 193/41 51 1111. C1. ..F16l 1/00, 365g15/08 [58] Field 61 Search ..61/72.1, 72.5, 72.6, 72.7, 61/723, 63, 41,43; 193/35, 38,41, 42

[56] References Cited UNITED STATES PATENTS 3,421,609 1/1969 Schmunk..61/72.5 x 2,979,178 4/1961 Harnre... ..193/41 x 2,704,143 3/1955Cushman ..193/35 2,790,887 4/1957 Gelfand ..49/246 x 10/1921 Chapman..61/72.3 9/1970 Blinne ..6l/72.6R

Primary Examiner-Jacob Shapiro Attomey-Giles C. Clegg, Jr. and Peter J.Murphy [57] ABSTRACT For laying a string of pipe, a main sled and thetrailer sled are adapted to be towed in a trench by a trenching machine.The sleds slide along the trench bottom on parallel runners and define agenerally continuous pipe supporting surface inclined downwardly fromthe leading end toward the trailing end. The sled supports the end ofthe assembled pipe string, the next pipe section to be joined to thestring for facilitating the assembly. The sleds are self centeringwithin the trench and carry implements for preparing the trench bottomto receive the pipe string.

13 Claims, 9 Drawing Figures PATENTEDM B 3.886.888

sum 2 or 2 MARION P HELTON ATTORNL BACKGROUND OF THE INVENTION Thisinvention relates to apparatus for use in assembling a string of pipesections and for laying the string of pipe on a ground surface.

The laying of pipe in ground trenches is an expensive and time consumingoperation. This invention is concerned with minimizing the expense ofsuch operation by providing apparatus for facilitating the assembly ofpipe sections into a string and for preparing the trench bottom toreceive and support the string of pipe in proper alignment within thetrench.

An object of this invention is to provide an improved, movable supportfor supporting the end of the string in convenient position to have thenext section of pipe joined to the string.

. Another object of this invention is to provide an improved, movablesupport defining an articulating train for accommodating curvature inthe ground path for the pipe string.

A further object of this invention is to provide an improved, movablesupport for laying a pipe string in a trench having means for preparingthe trench bottom surface for receiving and supporting the pipe string.

A still further object of this invention is to provide an improvedmovable apparatus for forming a pipe supporting bed at the bottom of atrench and for laying the pipe on said bed.

Still another object of this invention is to provide an improved pipelaying apparatus for forming a string from pipe sections having anenlarged bell at one end to define a joint with an adjacent pipesection.

These objects are obtained in a pipe laying sled havin g supportingrunners and adapted to be pulled along a pipe trench by a suitabletowing apparatus. The sled defines an upper pipe supporting surfaceinclined downwardly from the forward end toward the rearward end andhaving structure for supporting the enlarged bell end of one pipesection and the shank end of the additional section in axial alignmentfor the purpose of making the joint. At least one trailer sled iscoupled to a main sled, in train, to extend the supporting surface andprovide for articulation of the sled assembly. The sled may includemeans for lateral self-centering between the trench walls and forforming a ridge of loose dirt on the trench bottom to define a bed forsupporting the pipe string.

DRAWINGS The novel features of the invention, as well as additionalobjects and advantages thereof, will be understood more fully from thefollowing description when read in connection with the accompanyingdrawing, in which:

FIG. 1 is a top view of a preferred form of apparatus according to theinvention;

FIG. 2 is a side view of the apparatus of FIG. 1; FIG. 3 is aperspective view of the apparatus of FIG.

FIG. 4 is an elevation view of the forward end of the apparatus of FIG.1;

FIGS. 5 and 6 are fragmentary views of sectional views taken,respectively, along the Line 5-5 and Line 6-6 of FIG. 2 showing detailsof the pipe supporting surface;

FIG. 7 is a fragmentary sectional view taken along the Line 7-7 of FIG.2;

FIG. 8 is a view of a section of pipe; and

FIG. 9 is a transverse view of a pipe trench showing the pipe and asupporting bed therefor.

DESCRIPTION OF THE PREFERRED EMBODIMENT The preferred form of apparatusaccording to the invention, which is illustrated in the drawings, isparticularly adapted for use with pipe sections of the type shown inFIG. 8 including an elongated shank 6 having an enlarged bell 7 at oneend dimensioned for receiving the end portion 8 of an adjacent likesection to form a compression joint. Such pipe sections are joined toform a string by forceably compressing the mating ends together toachieve the desired sealed joint. Each end portion 8 may be tapered to adiameter slightly smaller than the shank portion 6 which comprises mostof the length of the pipe section.

As best seen in FIGS. 1, 2, and 3, the overall apparatus includes a mainsled 10 and at least one trailer sled 11 which are coupled together in atrainlike manner as will be described. In practice at least two trailersleds will most often be used although only one is required. Theapparatus is designed to be towed or pulled along the pipe trench bymeans of any suitable towing apparatus; and may be pulled by a ditchingmachine which is preparing the trench ahead of the pipe layingapparatus. The leading or forward end of the apparatus is viewed at theright in FIGS. 1, 2, and 3 of the drawings.

The main sled 10 is supported on a pair of parallel runners 12 which maybe fabricated of structural channels for example. The pipe supportingsurface of the main sled is preferably defined by a forward rollersection 13 at the forward end of the sled, and intermediate curved plateportion 14, and a rearward roller section 15.

The forward roller section 13 is supported on the runners 12 by means ofvertical legs 16 and 17, with appropriate transverse braces beingprovided for rigidity of structure. The rearward roller section 15 issupported on the rearward ends of the runners 12 by means of verticallegs 18 and 19 with suitable braces again being provided for rigidity ofstructure. The two roller sections are interconnected by a pair ofelongated cylindrical rods 20 which are secured to the tops of the sideframes of the forward and rearward roller sections to define side railsfor the pipe supporting surface. These rods 20 extend from the rearwardend of the sled 10 to a point short of the forward end of the sled andbridge the intermediate space between the forward and rearward rollersections. The rods 20 may be secured to the roller sections by means ofwelding or in any other suitable manner.

The curved plate portion 14, as best seen in FIGS. 2 and 5, consists ofan elongated plate section supported on the side rails 20 and beingformed to define a concave cylindrical trough 24 between the side rails20 and extending longitudinally between the two roller sections 13 and15. The side edges of the plate 14 are secured to the side rails bymeans of welding or in any other suitable manner.

The trough 24 is dimensioned to support and to confine laterally theenlarged bell end 7 of a pipe section during the assembly of theadjoining pipe section, the enlarged bell end being the exposed end ofthe last section to be joined to the string. The shank portion of thenext section to be joined to the string is supported on the forwardroller section 13; and, as best seen in FIG. 5, the rollers 23 of theroller section 13 define a supporting surface which lies above the baseof the trough 24. This difference in elevation may be one or two inchesfor example, so that the shank portion 6 of the section of pipe beingjoined to the string is supported in generally axial alignment with thebell portion 7 of the section to which it is being joined. As best seenin FIG. 6, the rollers 25 of the rearward roller section 15 are disposedto define an upper supporting plane which coincides with the base of thetrough 24, so that as the sled is moved forwardly from under theassembled pipe string, the bell joint will pass smoothly from the curvedplate portion 14 on to the rearward roller section 15.

As seen in the figures, the trailer sled 11 can be considerably shorterthan the main sled and is made up of a pair of parallel runners 27supporting a roller section 28 on vertical legs 29 and 30. Thisstructure may be fabricated in any suitable manner, such as by welding,with suitable cross braces for rigidity if desired. In coupled relationwith the main sled 10, the roller section 28 effectively provides acontinuation of the rearward roller section 15. The forward end 31 ofthe roller section 28 is inclined downwardly and the rollers in thisportion 31 define a plane inclined with respect to the plane of the mainsupporting surface to pick up the bell portion 7 of the pipe as the sledis moved forwardly relative to the pipe string.

The trailer sled 11 is coupled to the main sled 10 with a pair ofparallel tow bars 35 which are pivotally connected to the forward legs29 of the trailer sled 11, adjacent to the lower ends thereof, and tothe vertical legs 19 of the main sled 10, adjacent to the upper endsthereof. The tow bars 35 are pivotally connected to the legs by means ofhorizontal pins or bolts, so that the tow bars swing about horizontalaxes to provide for vertical articulation of the trailer sled 11relative to the main sled 10. In this manner, the joined sleds willaccommodate vertical undulations of the trench bottom or other surfaceupon which the pipe is being laid.

To provide for limited lateral articulation of the trailer sled 11relative to the main sled 10, the forward ends of the tow bars areprovided with longitudinally elongated slots 36 which receive therespective pivot pins of the main sled legs 19. The slots and pins,then, define lost motion connections between the tow bars and legs 19,permitting relative longitudinal movement so that the effective lengthsof the tow bars relative to each other may be changed. In this manner,the trailer sled 11 may swing laterally out of longitudinal alignmentwith the main sled 10 to accommodate lateral curvature of the trench;yet, with the pair of tow bars 35, good longitudinal tracking ismaintained.

As best seen in FIGS. 2, 3, and 7, the main sled 10 includes structurefor centering the sled between the walls of the pipe trench. An assemblyfor yieldingly engaging the trench wall is mounted on each side of thepipe sled 10. These assemblies are identical; and only one such assemblywill be described. As seen in the drawings, an elongated guide strap 40,preferably fabricated of a resilient metal, is supported between thelegs 16 and 17 extending generally parallel to the runner 12. Therearward end of the strap 40 is formed to define a bearing portion 41 toaccommodate a pivot pin suitably supported on the leg 17 betweenbrackets 42 for example. The forward end of the strap 40 is supportedand guided within a C-shaped bracket 43 mounted on the leg 16 to permitlongitudinal sliding of the strap 40 relative to the leg 17. A verticalleg 44 is secured between the runner l2 and the forward roller section13 approximately equidistant from the legs 16 and 17. A compressionspring 45 is connected between the leg 44 and the strap 40 to urge thecenter portion of the strap outward relative to the end supports, andtherefore to maintain an outwardly extending bow in the strap as viewedfrom the top of the sled. In this manner, when the sled is positionedwithin a pipe trench, the central portions of the straps 40, on eitherside of the sled, are urged outwardly into engagement with the sidewalls of the trench; and the straps are continuously and yieldinglyurged outwardly to accommodate variations in the side walls and varyingtransverse dimensions between the side walls, with similar forces actingat each side of the sled to maintain a central position within thetrench. As the bows in the straps 40 are increased or decreased, thesupporting brackets 43 for the forward ends permit longitudinal slidingmovement necessary to permit the changes in curvature.

As best seen in FIGS. 2, 3, and 4, the main sled 10 includes means forforming a ridge of loose dirt or other ground material to define a bedfor supporting the string of pipe at the bottom of the trench. Such aridge 9 is illustrated in FIG. 9 of the drawings, and is particularlydesirable for initially supporting the pipe string where the stringincludes enlarged bells 7 or couplings at the joints. The ridge 9 ofloose earth material will give way, as by spreading, at the joint 7 toprovide for uniform support of the string along the entire length. Themeans for forming the ridge includes two pairs of blades 47 and 48 whichare secured in any suitable manner to the inner walls of the runners 12and which extend inwardly toward each other to guide the loose materialtoward the central area between the runners. The lower edges of theblades may lie in the plane defined by the lower surface of the runners12, or lower, to scrape the trench bottom and form the central ridge 9.While not shown in the drawings, it may also be desirable to providemeans defining a transverse row of scarifying fingers to level any humpsin the trench bottom and to loose or break up the earth material to atexture or size appropriate for forming the supporting ridge 9.

The operation of the above described apparatus will now be brieflysummarized in connection with the laying of a string of pipe made up ofsections of pipe of the type described and illustrated in FIG. 9. Thesled assembly is positioned so that the curved plate portion 14underlies the bell portion 7 of the last section of pipe joined to thestring, which is then supported and confined by the trough 24. Thestring of pipe will be supported on the roller sections 28 of thetrailer sleds 11 until the string will rest on the trench bottom somedistance beyond the rearward end of the trailer sled l l.

The next section of pipe to be joined to the string is then placed onthe roller section 13 of the sled with its bell end forward and theshank 6 being supported on the rollers 23. If the forward end of thesled 10 is approximately at ground surface level, the pipe section maybe readily rolled from the ground surface onto the sled. This pipesection, guided by the side rails 20, is then pushed rearwardly on theroller section 13 toward the end of the string with the rollers 23defining a supporting plane for the shank above the base of the trough2d. The bell 7 at the end of the string is supported in the troughrelative to the roller section 13, so that the shank portion of the pipesection to be joined is axially aligned with the bell. The end 8 of thepipe section is readily engaged with the bell 7 at the end of the stringto make the compression joint.

When the joint is completed, the sled assembly is pulled forward by theditching machine or other suitable apparatus a distance equivalent tothe length of one pipe section, so that the bell portion of the pipesection just joined to the string is positioned in the trough 24. Duringthis movement of the sled assembly, the bell of the preceding sectionwill pass from the trough 24 onto rollers 25 of the roller section andwhen this bell passes beyond the sled 10, it will engage the inclinedportion 311 of the roller section 28 to be supported by this section.When the forward end of the sled 10 meets the bell portion of the pipesection just joined to the string, the inclined forward end portion 26of the roller section 13 will engage the bell to lift and support thebell in its movement toward the trough 24 as the sled is moved forward.

During the forward movement of the sled assembly, the guide straps 40will maintain the leading end of the sled 10 generally centered relativeto the side walls of the trench. If desired, an additional centeringassembly can be provided toward the rearward end of the sled.

Also during the forward movement of the sled assembly, the scraperblades 47 and 48 will form an elongated central ridge 9 of loose dirtalong the trench bottom as best seen in FIG. 9. This ridge forms a bedfor supporting the pipe string as it is laid on the trench bottom duringthe forward movement of the sled assembly. Since the bed is soft, beingformed of pulverized material, the ridge will give way by spreading whenit is engaged by a pipe bell 7, so that both the shank portions and thebell portions of the pipe string will be generally uniformly supportedby the ridge, with the pipe in appropriately aligned position from thetrench bottom. The supporting ridge 9 greatly minimizes the possibilitythat the bell joints will be broken or not provide a seal as the resultof misalignment to adjacent sections.

Although the invention has been described with reference to a particularpreferred embodiment, many changes and modifications will becomeapparent to those skilled in the art in view of the foregoingdescription which is intended to be illustrative and nonlimiting of theinvention defined in the claims.

What is claimed is:

1. Pipe laying apparatus, adapted to be moved along a pipe receivingtrench upon which a string of joined sections of pipe is being laid,comprising:

at least one frame having bottom runner means for sliding engagementwith the surface and inclined main support means for supporting, inalignment, the last section of pipe joined to the string and the nextsection of pipe to be joined to the string; said main support meansbeing inclined upwardly from the frame trailing end toward the frameleading end;

said main support means including a trough portion for supporting andlaterally locating the enlarged coupling end of the last section of pipejoined to the string and aforward section raised relative to said troughportion for supporting the shank of the next section of pipe to bejoined whereby the shank of the next section is supported in axialalignment with the supported coupling end;

said trough portion comprising a plate member supported on said framedefining a longitudinally extending concave trough for receiving theenlarged coupling end of a pipe section; and wherein said forwardsection defines a supporting surface lying above the base of said troughto support the shank portion of a pipe section in alignment with thecoupling end of the last section joined to the string.

2. Pipe laying apparatus as set forth in claim 1 further including arearward section for engaging and supporting the string of pipe; andwherein said forward and rearward pipe supporting sections are definedby roller means for engaging and supporting the pipe.

3. Pipe laying apparatus as set forth in claim ll including implementmeans mounted on said frame for forming a ridge of loose material at thebottom of said trench to provide a supporting bed for the string ofpipe.

4. Pipe laying apparatus as set forth in claim 1 wherein said bottomrunner means comprises at least one pair of spaced parallel runners; andblade means mounted on said runners, providing scraping edges in theplane of said runners for forming a ridge of said loose ground materialbetween said runners to provide a supporting bed for the string of pipe.

5. Pipe laying apparatus as set forth in claim 1 including centralizingmeans for laterally centering the apparatus in the trench; saidcentralizing means comprising a guide member mounted on each side ofsaid frame for lateral swinging movement into engagement with the wallsof the trench; and spring means yieldably urging each of said guidemembers outwardly relative to said frame into engagement with the trenchwalls.

6. Pipe laying apparatus as set forth in claim 1 including centralizingmeans for laterally centering the apparatus in the trench; saidcentralizing means comprising longitudinal, outwardly bowed springmembers mounted on each side of said frame; and spring means associatedwith each spring member for urging said member outward relative to saidframe into engagement with the wall of a ground trench.

7. Pipe laying apparatus as set forth in claim 6 wherein each of saidspring elongated members is pivotally attached at one end to said frame;and wherein the other end of said members is attached to said frame bymeans of a sliding coupling to permit longitudinal movement of saidother end relative to said frame.

a pipe receiving trench upon which a string of joined sections of pipeis being laid, comprising:

at least one frame having bottom runner means for sliding engagementwith the surface and inclined main support meansfor supporting, inalignment, the last section of pipe joined to the string and the nextsection of pipe to be joined to the string; said main support meansbeing inclined upwardly from the frame trailing end toward the frameleading end;

said main support means including a trough portion for supporting andlaterally locating the enlarged coupling end of the last section of pipejoined to the string and a forward section raised relative to saidtrough portion for supporting the shank of the next section of pipe tobe joined whereby the shank of the next section is supported in axialalignment with the supported coupling end;

at least one trailer frame having bottom runner means and inclined pipesupporting means; said first named main frame and said trailer frameproviding a generally aligned pipe supporting surface; said at least onetrailer frame providing a pipe supporting surface between said mainsupport means and the bottom of the trench;

means coupling said trailer frame to said main frame to provide forvertical and lateral articulation of said frame;

each of said trailer frames and said main frame includes roller meansdefining the pipe supporting surfaces; and wherein said trailer framesupporting surface includes a downwardly inclined forward edge to engagethe enlarged diameter portions of the pipe sections.

9. Pipe laying apparatus as set forth in claim 8 wherein said couplingmeans comprises a pair of parallel tow bars pivotally connected to boththe main frame and the trailer frame adjacent to the sides thereof, saidtow bars being pivoted about horizontal axes;

and one end of each of said tow bars having a longitudinally elongatedslot means defining a respective pivotal connection and permittinglongitudinal dinally elongated slot at one end coacting with ahorizontal pivot shaft to define a lost motion connection providing forlimited lateral articulation of said trailer frame relative to said mainframe.

12. Pipe laying apparatus as set fOIIHl in claim 8 mclu mg means mountedon sat main frame for laterally centering the apparatus in the trench.

13. Pipe laying apparatus, adapted to be moved along a pipe receivingtrench upon which a string of 10 joined sections of pipe is being laid,comprising:

movement of the tow bar and pivot means to pro- I vide for limitedlateral articulation of the trailer frame relative to the main frame.

10. Pipe laying apparatus as set forth in claim 8 wherein said couplingmeans includes a pair of laterally spaced tow bars pivotally connectedbetween said main frame and the trailer frame; each end of the tow barand the associated frame defining pivot means for vertical articulationof the trailer frame relative to the main frame;

and the pivot means on one end of each of said tow bars including meanspermitting relative longitudinal movement of the tow bar relative to theframe to provide for limited lateral articulation of the trailer framerelative to the main frame.

1 1. Pipe laying apparatus as set forth in claim 10 wherein each of saidtow bars includes a longitu a main frame having bottom runner meansforsliding engagement with the surface and inclined support means forsupporting in alignment the last section of pipe joined to the stringand the next section of pipe to be joined to the string; said supportmeans being inclined upwardly from the frame trailing end toward theframe leading end;

said main frame inclined support means including forward and rearwardsections defined by roller means for engaging and supporting the pipe,and a trough portion defined by a curved plate member mounted on saidframe between said forward and rearward support sections for supportingand laterally confining the enlarged coupling end of the last pipesection joined; said forward support section defining a supportingsurface lying above the base of said trough to support the shank portionof the next pipe section to be joined in alignmerit with the couplingend of the last section joined to the string;

at least one trailer frame having bottom runner means and an inclinedpipe supporting surface defined by roller means, said main frame andsaid at least one trailer frame providing a generally aligned pipesupporting surface, with said at least one trailer frame providing apipe supporting surface between said main frame and the bottom of thetrench;

means coupling said trailer frame to said main frame comprising a pairof parallel tow bars pivotally connected to both the main frame and thetrailer frame adjacent to the sides thereof; said tow bars being pivotedabout horizontal axis, and one end of each of said tow bars having alongitudinally elongated slot means defining a respective pivotalconnection and permitting longitudinal movement of the tow bar and pivotmeans to provide for limited lateral articulation of the trailer framerelative to the main frame;

centralizing means mounted on said main frame for centering theapparatus in the trench; said centralizing means comprising a guidemember mounted on each side of said frame for lateral swinging movement,and spring means yieldably urging each of said guide members outwardlyrelative to said frame into engagement with the trench walls;

and implement means mounted on said frame for forming a ridge of loosematerial at the bottom of said trench between said runners to provide asupporting bed for the string of pipe.

1. Pipe laying apparatus, adapted to be moved along a pipe receivingtrench upon which a string of joined sections of pipe is being laid,comprising: at least one frame having bottom runner means for slidingengagement with the surface and inclined main support means forsupporting, in alignment, the last section of pipe joined to the stringand the next section of pipe to be joined to the string; said mainsupport means being inclined upwardly from the frame trailing end towardthe frame leading end; said main support means including a troughportion for supporting and laterally locating the enlarged coupling endof the last section of pipe joined to the string and a forward sectionraised relative to said trough portion for supporting the shank of thenext section of pipe to be joined whereby the shank of the next sectionis supported in axial alignment with the supported coupling end; saidtrough portion comprising a plate member supported on said framedefining a longitudinally extending concave trough for receiving theenlarged coupling end of a pipe section; and wherein said forwardsection defines a supporting surface lying above the base of said troughto support the shank portion of a pipe section in alignment with thecoupling end of the last section joined to the string.
 2. Pipe layingapparatus as set forth in claim 1 further including a rearward sectionfor engaging and supporting the string of pipe; and wherein said forwardand rearward pipe supporting sections are defined by roller means forengaging and supporting the pipe.
 3. Pipe laying apparatus as set forthin claim 1 including implement means mounted on said frame for forming aridge of loose material at the bottom of said trench to provide asupporting bed for the string of pipe.
 4. Pipe laying apparatus as setforth in claim 1 wherein said bottom runner means comprises at least onepair of spaced parallel runners; and blade means mounted on saidrunners, providing scraping edges in the plane of said runners forforming a ridge of said loose ground material between said runners toprovide a supporting bed for the string of pipe.
 5. Pipe layingapparatus as set forth in claim 1 including centralizing means forlaterally centering the apparatus in the trench; said centralizing meanscomprising a guide member mounted on each side of said frame for lateralswinging movement into engagement with the walls of the trench; andspring means yieldably urging each of said guide members outwardlyrelative to saId frame into engagement with the trench walls.
 6. Pipelaying apparatus as set forth in claim 1 including centralizing meansfor laterally centering the apparatus in the trench; said centralizingmeans comprising longitudinal, outwardly bowed spring members mounted oneach side of said frame; and spring means associated with each springmember for urging said member outward relative to said frame intoengagement with the wall of a ground trench.
 7. Pipe laying apparatus asset forth in claim 6 wherein each of said spring elongated members ispivotally attached at one end to said frame; and wherein the other endof said members is attached to said frame by means of a sliding couplingto permit longitudinal movement of said other end relative to saidframe.
 8. Pipe laying apparatus, adapted to be moved along a pipereceiving trench upon which a string of joined sections of pipe is beinglaid, comprising: at least one frame having bottom runner means forsliding engagement with the surface and inclined main support means forsupporting, in alignment, the last section of pipe joined to the stringand the next section of pipe to be joined to the string; said mainsupport means being inclined upwardly from the frame trailing end towardthe frame leading end; said main support means including a troughportion for supporting and laterally locating the enlarged coupling endof the last section of pipe joined to the string and a forward sectionraised relative to said trough portion for supporting the shank of thenext section of pipe to be joined whereby the shank of the next sectionis supported in axial alignment with the supported coupling end; atleast one trailer frame having bottom runner means and inclined pipesupporting means; said first named main frame and said trailer frameproviding a generally aligned pipe supporting surface; said at least onetrailer frame providing a pipe supporting surface between said mainsupport means and the bottom of the trench; means coupling said trailerframe to said main frame to provide for vertical and lateralarticulation of said frame; each of said trailer frames and said mainframe includes roller means defining the pipe supporting surfaces; andwherein said trailer frame supporting surface includes a downwardlyinclined forward edge to engage the enlarged diameter portions of thepipe sections.
 9. Pipe laying apparatus as set forth in claim 8 whereinsaid coupling means comprises a pair of parallel tow bars pivotallyconnected to both the main frame and the trailer frame adjacent to thesides thereof, said tow bars being pivoted about horizontal axes; andone end of each of said tow bars having a longitudinally elongated slotmeans defining a respective pivotal connection and permittinglongitudinal movement of the tow bar and pivot means to provide forlimited lateral articulation of the trailer frame relative to the mainframe.
 10. Pipe laying apparatus as set forth in claim 8 wherein saidcoupling means includes a pair of laterally spaced tow bars pivotallyconnected between said main frame and the trailer frame; each end of thetow bar and the associated frame defining pivot means for verticalarticulation of the trailer frame relative to the main frame; and thepivot means on one end of each of said tow bars including meanspermitting relative longitudinal movement of the tow bar relative to theframe to provide for limited lateral articulation of the trailer framerelative to the main frame.
 11. Pipe laying apparatus as set forth inclaim 10 wherein each of said tow bars includes a longitudinallyelongated slot at one end coacting with a horizontal pivot shaft todefine a lost motion connection providing for limited lateralarticulation of said trailer frame relative to said main frame.
 12. Pipelaying apparatus as set forth in claim 8 including means mounted on saidmain frame for laterally centering the apparatus in the trench.
 13. Pipelaying apParatus, adapted to be moved along a pipe receiving trench uponwhich a string of joined sections of pipe is being laid, comprising: amain frame having bottom runner means for sliding engagement with thesurface and inclined support means for supporting in alignment the lastsection of pipe joined to the string and the next section of pipe to bejoined to the string; said support means being inclined upwardly fromthe frame trailing end toward the frame leading end; said main frameinclined support means including forward and rearward sections definedby roller means for engaging and supporting the pipe, and a troughportion defined by a curved plate member mounted on said frame betweensaid forward and rearward support sections for supporting and laterallyconfining the enlarged coupling end of the last pipe section joined;said forward support section defining a supporting surface lying abovethe base of said trough to support the shank portion of the next pipesection to be joined in alignment with the coupling end of the lastsection joined to the string; at least one trailer frame having bottomrunner means and an inclined pipe supporting surface defined by rollermeans, said main frame and said at least one trailer frame providing agenerally aligned pipe supporting surface, with said at least onetrailer frame providing a pipe supporting surface between said mainframe and the bottom of the trench; means coupling said trailer frame tosaid main frame comprising a pair of parallel tow bars pivotallyconnected to both the main frame and the trailer frame adjacent to thesides thereof; said tow bars being pivoted about horizontal axis, andone end of each of said tow bars having a longitudinally elongated slotmeans defining a respective pivotal connection and permittinglongitudinal movement of the tow bar and pivot means to provide forlimited lateral articulation of the trailer frame relative to the mainframe; centralizing means mounted on said main frame for centering theapparatus in the trench; said centralizing means comprising a guidemember mounted on each side of said frame for lateral swinging movement,and spring means yieldably urging each of said guide members outwardlyrelative to said frame into engagement with the trench walls; andimplement means mounted on said frame for forming a ridge of loosematerial at the bottom of said trench between said runners to provide asupporting bed for the string of pipe.